Fuel pump



y 1947. w. E w. NICOLLS 2,424,943

FUEL PUMP Filed March 15, 194A Patented July 29, 1947- FUEL PUMP wannaEdward Walter England, assignor to land Application March 15 In GreatBrita! This invention relates to systems for supplying liquid fuel insmall measured quantities to the cylinder or cylinders of an internalcombustion engine, and of the kind having in combination an injectionpump adapted for connection to an injection nozzle, or a plurality ofsuch pumpsimproved form of injection pump for use in a system of thekind specified above.

The accompanying drawing is a sectional elevation of a liquid fuelinjection pump system embodying an injection pump in accordance with theinvention.

The liquid fuel system shown in the drawing comprisesan injection pump aor a plurality of such pumps, and a variable-delivery metering pump badapted to supply liquid fuel to the injection pump or pumps, the solefunction of the injection pump or each such pump being to dischargethrough an associated nozzle the fuel received from the metering pump.

In constructingthe injection pump a, or each such pump, 'I employa.cylindrlcal body part d adapted to be inserted in and secured to oneend of the cylinder or one of the cylinders'of an internal combustionengine. At its inner end the body part d has secured to it the injectionnozzle c which may be of any desired form, the interior of the nozzlebeing fitted with a spring loaded non-return valve e. Along the axis ofthe body part 41 is formed a passage 1 which extends between the nozzle0 and a, cylindrical chamber a formed in the outer end of the body part.At a position adjacent to the chamber a the passage 1 communicatesthrough a branch passage h with a fuel inlet pipe connection i, thelatter being detachably secured to the body part 41, and beingcontrolled by-a non-return valve :5. In the chamber g is secured a pumpbarrel is which extends from the outer end of the body part d, the innerend of the bore of the barrel being open to the axial passage f in thebody part. Also around an intermediate part of the exterior of thebarrel k is formed (either in the barrel or in the body part :1)an'annular gallery m which communicates at one side with a lateral pipeconnection n through which lubricating oil or other convenient auxiliaryliquid can be supplied. Also in the portion of the barrel k surroundedby the gallery m Nicolla, Ealing, London. 0. A. V. Limited. London,

, 1944, Serial No. 526,558

n February 26, 1943 2 Claims. (01. 1025-41) non-return valves as 6'.Slidable are formed two sets of ports leading to the bore of the barrel,one set of these ports (herein termed the upper set) being indicated by0, and the other set (herein termed the lower set) being indicated by p.

The barrel it contains two coaxial plungers q, r. The plunger q, whichforms the actuating member of the pump. is a long one and it extendsfrom about the position of the upper set of ports 0 to beyond the outervend of the barrel k. The outer end of this plunger q is provided with ahead 3 on which acts a rocker arm t for moving the plunger inwards and aspring a for moving the plunger outwards. The arm t is actuated by a camv, and the latter is carried on a cross shaft 10 which (when the engineto be supplied with liquid fuel is a multi-cylinder engine) is common toall the engine cylinders and is provided with the cams required foractuating all the injection pumps. The other plunger r, which forms thefuel injecting member of the pump, is a relatively short one andconsists of a cylindrical piece freely slidable in the bore oi thebarrel is. This plunger 1' is situated in the portion of the barrel borebetween the ant. It is not essential, however, that the metering pump bshall be capable of operating at the normal high pressures, as its soleduty is to feed the injection pump or pumps as a. In the example shownthe metering pump b is of the multipledelivery swash plate type, andcomprises a hollow casing 2 in which a plurality of ported pumpcylinders 3 are mounted around a common inlet pipe connection 4, and areprovided at their outer ends with outlet pipe connections 5 controlledby within and extending from the inner ends of the pump cylinders 8 areplungers as l which are also rotatable about their longitudinal axes.The plungers l are slidable in one direction by springs 8 and in theopposite direction by a rotatable swash plate 9, the latter beingadapted to be driven-by the engine. Movements of the plungers 1 by thespring a cause fuel from the inlet connection t to be drawn into thepump cylinders 3 through port 10 in the cylinder walls, and movements ofthe plungers by the swash plate 9 serve to discharge-fuel from thecylinders through the outlet connections 5. The inner ends of theplungers I are made so that the output of the'pump b can be varied inthe usual manner by rotational movements of the plungers about theirlongitudinal axes. Such rotational movements may be imparted to theplungers 1 either by hand or automatically from a lever II on a spindle1'2, the latter being connected by toothed gearing I; to sleeves llwhich surround the cylinders 3 and engage notched collars as I! on theinner ends of the plungers,

It will be understood that each of the outlet pipe connections 5 of themetering pump 1) is connected to the inlet pipe connection 1 of aninjection pump a as above described.

The injection pump a or each such pump operates in the following manner.Lubricating oil or other auxiliary liquid is supplied through the 4plunger slidable in the bore and extending through its outer end, asecond plunger arranged coaxially with the actuating plunger in theinner end of the bore so that thesecond plunger is movable relatively tothe actuating plunger by and to an extent dependent on the quantity ofliquid fuel supplied to the inner end of the bore, the adjacent ends ofthe two plungers being spaced apart, ports which communicate under thecontrol of the plungers with the space between the adjacent ends of theplungers, and through which an auxiliary liquid under pressure can flowinto and out of the said space, an outlet through which liquid fuelsupplied to the inner end of the bore can be discharged by movementimparted to the second plunger from the actuating plunger through themedium of the auxiliary liquid between the adjacent ends of theplungers,

pipe connection 11. to the gallery 111. and the space between theadjacent ends of the plungers -q, r at a moderate pressure. When acharge is received from the metering pump 1) the effect of this chargeis to push the injection plunger 1' upw'ards to an extent dependent onthe volume of the charge, a corresponding quantity of the auxiliaryliquid being displaced by this movement from the barrel bore through theports 0, 12, both sets of which are initially uncovered by the plungersq, r. In this action plunger 1' moves suiilciently to close the lowerports 9. Later the actuating plunger q is moved inwards by its cam 12causing a further displacement of the intervening liquid and closing theupper ports 0. Continued movement of the actuating plunger q causesmovement of the injection plunger 1- through the medium of the entrappedauxiliary liquid and thereby eifects the injection through the nozzle cof the quantity of fuel received from the metering pump 1), theinjection ceasing when the lower ports 1: are uncovered. After injectionthe actuating plunger or returns under the action of its spring u, and

auxiliary liquid flows back into the space between the plungers q, 1' inreadiness for the next cycle of operations.

In the example shown the upper ports 0 are of circular cross section,but this is not essential as these ports may have any other suitablecross sectional shape.

By means of injection pumps constructed and operating as abovedescribed, I am able to attain the desired results in a very simple andsatisfactory manner.

The invention is not, however, limited to the example above described assubordinate details may be varied to suit requirements. Thus, thepositions of the nozzle and outlet pipe connection of the injection pumpor each such pump may be interchanged.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid fuel pump having in combination a body, aninlet throughwhich measured quantities of liquid'fuel can be supplied under pressureto the inner end of a bore in the body, an actuating the injection andmeans for imparting reciprocatory movements to the actuating plunger.

2. A liquid fuel pump having in combination a cylindrical body part, achamber in the body part, a barrel secured in and extending from one endor the chamber, an inlet through which measured quantities of liquidfuel can be supplied under pressure to the inner end of the barrel bore,an actuating plunger slidable in the barrel bore and extending throughits outer end, a second plunger arrangedcoaxially with the actuatingplunger in the inner end of the barrel bore so that the second plungeris movable relatively to the actuating plunger by and to an extentdependent'on the quantity of liquid fuel supplied to the inner end ofthe barrel bore, the

adjacent ends of the two plungers being spaced apart, a gallerysurrounding the barrel and having an inlet through which an auxiliaryliquid under pressure can be supplied to the gallery, ports formed inthe barrel at positions near the adjacent ends of the plungers, andserving under the control of the plungers to allow flow of the auxiliaryliquid between the gallery and the space separating the adjacent ends ofthe plungers, an outlet passage which communicates with the inletpassage, and through which liquid fuel supplied to the inner end of thebarrel bore can be discharged by movement imparted to the second plungerfrom the actuating plunger through the medium of the auxiliary liquidbetween the adjacent ends of the plungers, and means for im partingreciprocatory movements to the actuating plunger.

, WILFR-ID EDWARD WALTER NICOLLS.

REFERENCES CITED 'I 'he following references'are of record in the fileof this patent:

UNITED STATES PATENTS Tabb Nov. 11, 1941

